Various support options are available for tup depending on your needs and your project.
Public mailing list: http://groups.google.com/group/tup-users
Free for Open Source and commercial projects. Any emails sent to the mailing list are archived and available publicly. In general, most users will want to use this option. This guarantees that your issue will be seen by the most people, and it helps others who may be searching for similar questions. It does not matter if your project is Open Source or commercial - all emails to the public mailing list will be treated the same.
Private email to the author: email@example.com
Free for Open Source projects. This option is available if you don't want to discuss the details of your project in a public forum. Here, "Open Source" means software under any license designated as Open Source by the Open Source Initiative: http://www.opensource.org/licenses/alphabetical